Michael Dukakis was a Democrat candidate running for President in 1988. He had previously been criticized as being soft on national defense, so in September of that year he orchestrated a photo op in an M1 Abrams tank meant to toughen up his image.
The public found the image of Dukakis in the oversized safety helmet comical, and the photo op had the opposite of the intended effect of making him look tough. So much so that his opponent, George H.W. Bush used footage of Dukakis’ tank ride in his own advertisements.
My understanding is that Michael Cohen paid out of his own pocket and was reimbursed by the campaign effectively (as you noted) being an unreported contribution. But that aside, we used to hold candidates to a standard - Dukkakis’s photo op, Hart’s boat trip, Dean’s silly yell - that was the end of their run. Trump literally cheats on his wife, talks about fondling women, is…himself over and over and quite literally takes the unprecedented step of refusing to gracefully cede power and…he still thrives. It’s beyond parody.